Last edited 25 Nov 2021

Main author

Michael Heaton Other Consultant Website

Archaeology and construction

Historic environment.jpg


[edit] Introduction

Protection of archaeological remains, including historic buildings, has been a part of the British planning systems since the early 1990s and is now addressed by Section 12 of the National Planning Policy Framework (NPPF).

All designers of refurbishment or extension projects affecting 'historic' buildings, and all designers of new buildings within areas that the local planning authority (LPA) believes to be archaeologically sensitive, need to be aware of the requirements of the NPPF and the preceding planning guidance statutory instruments it is based on - in particular; PPG16 (1990), PPG14 (1994) and PPS5 (2010).

The revised NPPF (February 2019) makes clear that 'there will be archaeological interest in a heritage asset if it holds, or potentially holds, evidence of past human activity worthy of expert investigation at some point. Heritage asset is defined as 'a building, monument, site, place, area or landscape identified as having a degree of significance meriting consideration in planning decisions, because of its heritage interest. It includes designated heritage assets and assets identified by the local planning authority (including local listing)'.

The NPPF makes no distinction between archaeological sites and historic buildings, or between designated - i.e. 'Listed' or 'Scheduled' - or un-designated entities: all are referred to as 'heritage assets'.

Fortunately, there is a lot of guidance available, including the Chartered Institute of Building (CIOB) guidance of 1994 and the recent Chartered Institution of Building Services Engineers (CIBSE) guide; Historic England continues to produce authoritative guidelines on most aspects of the 'historic environment' and many LPAs do so as well.

The Institution of Civil Engineers (ICE) has also produced a useful guide to accompany their Conditions of Contract for Archaeological Investigations, which remains the only bespoke standard form contract for archaeological works. The Association of Local Government Archaeological Officers also produced a very useful guide to the control of works affecting historic buildings that is available from them c/o Essex County Council.

[edit] Procedure

Applicants, which in most cases means their professional advisers, have to demonstrate, in their planning or listed building consent applications that they are aware of all 'heritage assets' potentially affected by a design proposal, that they understand the 'significance' of those assets and that the design does not deleteriously affect that 'significance'.

Applicants and their designers should assume that all applications should be accompanied by a 'heritage statement' of some sort, even if it is just a paragraph saying 'there are no known or likely heritage assets affected by the proposals'.

Where impact is unavoidable, for instance in the few cases where the public benefit of the proposals outweighs the heritage impact, the applicant will be required to commission 'mitigatory' works.

In the case of archaeological sites that will entail archaeological excavation, analysis of the results and an appropriate form of public dissemination - such as an article in an archaeological journal. In the case of historic buildings, it can mean 'building recording' - i.e. record surveys.

[edit] How is this done?

All local planing authorities employ, or retain the services of, archaeological officers whose job it is to vet all planning applications and maintain a database of all known archaeological remains - known as the Historic Environment Record (HER). Most HERs also contain records of listed buildings and other 'heritage assets' and many are accessible through the internet, though the information invariably needs filtering or interpreting by a knowledgeable person.

Archaeological officers, in theory, perform an identical role to conservation officers, but in truth they are very different and respond differently to development and building proposals. You will generally find them to be helpful and constructive. Some LPAs employ a single person for both jobs, and others allow their archaeological officers to advise their conservation officers, and vice versa.

For archaeological sites, the LPA's archaeological officer will consult the HER and take a view as to whether the proposed development will affect archaeological remains. If they believe there is a reasonable risk of that, they will ask the applicant to provide verifiable information on the nature and significance of those archaeological remains. That can be done through a desk-study type report, but invariably the LPA will ask for that to be corroborated by some form of site investigation, so it may be more efficient to commission a site investigation immediately.

Archaeological site investigation is usually referred to as 'evaluation'. Desk studies have value in their own right only where there is a need for due diligence, or where the desk study is likely to prove that there is no need for evaluation.

There are plenty of specialist contractors able to undertake 'evaluations', most with websites and yellow pages entries, and many are listed by the Institute for Archaeologists (this is the trading name of the Institute of Field Archaeologists) which has been granted chartered status. Evaluation is analogous to geotechnical site investigation (albeit with different trench configurations) and the costs, times and lead-in times are likely to be comparable.

When an evaluation demonstrates that the proposed development site contains significant (which is a movable feast) archaeological remains that cannot be protected by redesigning the proposals, the LPA will attach a condition to planning permission requiring the archaeological 'excavation' of those remains. An 'excavation' contract proceeds through three stages:

The last two stages are carried out off-site once construction has commenced, but can run for years on large or complex sites and will often still be running long after the defects liability period or even contractual liability period for the building works have expired. Post-excavation analysis and publication costs will often be between 30% and 50% of site operation costs. It is a tried and tested strategy that works well and most archaeological contractors are highly experienced in it.

The process for works affecting historic buildings is slightly more complex, mainly because most conservation officers are not primarily concerned with the archaeological potential of historic buildings - or at least don't have the time or resources to do so. All historic buildings embody interpretable archaeological information concerning the people who designed and used those buildings, much of it not available from other sources.

That information is embodied in the layout, structure and fabric of the building and can be recorded and analysed archaeologically. In the UK, this is referred to as 'buildings archaeology'; German speakers refer to it as 'historische bauforschung' or just 'bauforschung'. The NPPF requires assessment and / or evaluation of a building's archaeological potential.

Where it cannot be preserved, a detailed record survey should be made. Invariably, that record survey can be made only while refurbishment is underway, because it is not until finishes start coming off and demolition starts that the historic fabric can be observed and recorded. Accordingly, it is inherently difficult to cost in advance, but it will rarely cost more than a few % of overall construction costs and there are plenty of specialist contractors willing to do it.

Managed intelligently and with foresight, archaeology need not inconvenience any construction project. That often requires engagement with professional archaeologists at an early stage, preferably through the agency of an architect or designer with an established relationship with archaeologists. Some even employ their own.

This article was created by --Michael Heaton 28th February 2014

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